Hi, You have the platform there in the middle, grapple up break time seal,
Now go to the bell on the right jump up and do the prompt, when Krato's lets go of the bell slow time, jump/fly towards the platform and grapple up drop down on the platform and R1 the ringer there, if done right the statues face will crack, the sounds have to over lap, if not repeat,
After face crack jump down in water under bell ringer there is a handle grab and turn, you will get a cut scene showing under water a pin, turn the handle till the pin is over a notch, now go under water to find a lever there pull it, the platform is now unlocked you now go back to the handle and turn the bell ringer towards the face and grapple back up and pull the ringer..Good Luck